1. Technical Field
The present invention relates to a film used for wrapping vegetables and fruit, particularly to a film for wrapping vegetables and fruit which adsorbs an ethylene gas to exert an excellent effect for keeping freshness of vegetables and fruits.
2. Background Information
It has hitherto been known that the storage condition of vegetables and fruit depends upon the amount of the resulting ethylene gas evolved from themselves, and that the time for which freshness of vegetables and fruit is freshly maintainable can be remarkably prolonged by removing the ethylene gas in a storage house, when vegetables and fruit are stored.
Vegetables and fruit themselves evolve the ethylene gas to ripen. In a sealed storage house, the concentration of ethylene evolved from vegetables and fruit themselves is increased. As a result, their ripeness is enhanced and their freshness is rapidly decreased.
Therefore, in order to keep freshness of vegetables and fruit, it is an important problem to depress the evolution of ethylene and to remove the evolved ethylene gas.
For example, Japanese Patent Publication No. 55-50451/1980 discloses a material for storing vegetables and fruits, keeping their freshness by removing the ethylene gas, wherein bromine is adsorbed in carbon having fine pores of a few angstrom diameter.
However, the material for keeping the freshness as described in the above specification is placed in a storage house and intended to remove the whole ethylene gas therein. Accordingly, a large quantity of the material for keeping the freshness is required. Moreover, it is difficult to remove ethylene completely. In particular, the ethylene gas which is considerably high in concentration stays on the surface of each of vegetables and fruit. It is extremely difficult to remove this ethylene gas completely. It has been, therefore, extremely difficult to keep freshness of vegetables and fruit for a long period of time.
Also, when a small amount of vegetables and fruit are stored, there have been problems that the operation requires much time and is complicated, and that the storage cost becomes high, because the material for keeping the freshness must be placed in a storage house each time.